CN113162215B - Emergency power supply system and control method for replacing offshore platform diesel generator system - Google Patents

Abstract

The invention discloses a novel emergency power supply system for replacing an offshore platform diesel generator system and a control method, and belongs to the field of power systems. The emergency power supply system comprises energy storage system equipment, low-voltage power distribution system equipment and auxiliary system equipment; when the offshore platform is used as an emergency power supply, the problems of difficult operation and maintenance, slow starting, low integration level and the like exist. The invention adopts battery energy storage as a novel emergency power supply of the offshore platform, makes reasonable energy storage capacity selection through requirements, makes a control strategy suitable for the offshore platform, and has the advantages of quick response time, convenient operation and maintenance, convenient control, high electrified integration level, reduction of fuel oil danger and the like.

Description

Emergency power supply system and control method for replacing offshore platform diesel generator system

technical field

The invention relates to the field of electric power systems, in particular to a new emergency power supply system and a control method for replacing diesel generator systems on offshore platforms.

Background technique

Judging from the current situation of wind resources development and planning, domestic onshore wind farm resources available for development are limited, and the development of offshore wind farms has become the only way to further develop wind power in coastal areas.

Due to the advantages of traditional diesel generator technology, such as mature technology and low equipment cost, at present, offshore wind farms in Europe, offshore wind farms and offshore oil platforms that have been built or are under construction in my country all use diesel generators as offshore platforms (converter stations) emergency power supply. Diesel power generation system has mature technology, fewer power electronic components, good quality of basic parts and spare parts, good integration, less difficulty in daily maintenance and installation, and flexible and convenient operation. However, the diesel power generation system supplies power for emergency loads, and there are some common problems: ① In terms of operation and maintenance, the working environment on offshore platforms is harsh, and the frequency of startup is low. Less operation and maintenance work. At the same time, the diesel engine power supply system needs to be equipped with diesel, and the diesel engine room and the oil tank room are respectively set up. After the diesel is consumed once, human intervention is required to transport the diesel to the sea. ②In terms of start-up, the start-up time of the diesel power generation system is relatively long, which can reach more than ten seconds or even longer, and there is also the problem of start-up failure after self-starting. ③ In terms of control, the control of the diesel power generation system itself depends on the low-voltage power distribution system and other control systems to send control commands, and the system integration is relatively low. ④ From the aspect of environmental protection. Diesel engine combustion has the disadvantages of high emission and high pollution.

In recent years, with the vigorous development of offshore wind power, the construction of offshore wind farms has gradually developed from short distances to deep seas. This undoubtedly poses an increasing challenge to the daily operation and maintenance of diesel power generation systems. As an industry that has developed rapidly in recent years, energy storage battery technology has many engineering applications in onshore microgrids and emergency energy. The invention integrates the energy storage system into the emergency power supply system of the offshore wind farm for the first time. Solve the problems of difficult operation and maintenance, slow startup, and low integration when the diesel power generation system is used as an emergency power supply.

Based on the above situation, the present invention proposes a new emergency power supply system and control method to replace the offshore platform diesel generator system, which can effectively solve the above problems.

Contents of the invention

Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a new emergency power supply system that replaces the diesel generator system on the offshore platform. It is used to solve the problems of poor stability, low reliability, difficult operation and maintenance, and high operation and maintenance costs of diesel power generation systems on offshore platforms. At the same time, a control method for emergency energy storage power systems that can achieve this purpose is given.

In order to solve the problems of the technologies described above, the present invention is realized through the following technical solutions:

In the first aspect, the present invention provides a new emergency power supply system that replaces the diesel generator system on the offshore platform, including energy storage system equipment, low-voltage power distribution system equipment and auxiliary system equipment; the energy storage system equipment is mainly composed of an isolation step-up transformer, Energy storage bidirectional converter, energy storage battery pack, local controller, energy storage load controller, dual power switching device and ATS fast switching switch; low-voltage power distribution system equipment is mainly composed of low-voltage power distribution system and emergency power distribution system The output terminal of the low-voltage power distribution system is connected to the dual power switching device, and the output terminal of the dual power switching device is connected to the ATS fast switch; the first output terminal of the ATS fast switch is connected to the emergency power distribution system, and the first output terminal of the ATS fast switch The two output terminals are connected to the isolation step-up transformer and charged to the energy storage battery pack through the energy storage bidirectional converter, and the output terminal of the isolation step-up transformer is connected to the emergency power distribution system, which can be connected to the local controller through the ATS fast switching switch It is used to control the switching between grid-connected mode and off-grid mode.

Wherein, the energy storage battery pack includes any normal energy storage battery that can be repeatedly charged and discharged, such as lithium-ion batteries, lead-acid batteries, fuel cells, and the like. The energy storage load controller is any PLC controller that can meet the requirements of the control strategy of the present invention. The ATS fast transfer switch can only detect whether the system is powered off after the dual power switching device detection action cycle is completed, so as to ensure that there is no switch jitter phenomenon.

As a preferred technical solution of the present invention, the auxiliary system equipment includes a fire control system and an environment control system, the fire control system includes fire monitoring equipment and fire extinguishing equipment, and the environment control system includes ventilation and temperature control equipment.

Emergency power distribution loads include offshore platform emergency lighting, offshore platform lifeboat power supply, offshore platform signal lights and sound signals, offshore platform navigation, etc., offshore platform environmental control system, offshore platform fire protection system, offshore platform fire alarm equipment, fire broadcasting equipment, offshore Platform emergency communication equipment. The offshore platform includes various offshore platforms such as an offshore oil and gas platform, an offshore wind power generation platform, an offshore converter station platform, and an offshore power distribution system platform.

As a preferred technical solution of the present invention, the low-voltage power distribution system is equipped with two transformers for stations, and two sections of low-voltage power distribution buses are arranged. One station transformer is connected to the low-voltage section I busbar, and the other station transformer is connected to the low-voltage section II busbar. Section bus, I section and II section are connected by bus coupler.

As a preferred technical solution of the present invention, when the thyristor in the ATS fast transfer switch fails or the system is overhauled, the bypass circuit breaker can be closed to ensure uninterrupted power supply to the load, and the system works in bypass mode at this time.

The configuration of the battery capacity of the energy storage battery pack is based on the emergency load power, power supply time, and actual capacity, and the energy storage battery pack capacity selection formula ^{[1] [2]} is obtained.

[1]

[2]

R——system capacity

R' - system available capacity

u——system efficiency

u1——energy storage battery efficiency

u2——energy storage bidirectional converter efficiency

u3——Isolation Transformer Efficiency

u4——Efficiency after considering other losses of the system

μ——discharge depth

γ——battery decay

When the grid-side power system is normal, any one of the two low-voltage distribution incoming lines on the system side supplies power. When the incoming circuit of this section loses power, the dual power switching device switches to the live circuit for power supply; when the other incoming circuit loses power, the dual power switching device that continues to maintain the power supply of this section does not operate. At this time, the ATS fast switching switch is always closed, and the energy storage system is in a state of floating charge. In this state, the whole system works in grid-connected operation mode.

When the incoming lines at both ends of the system side lose power, the ATS fast switching switch first detects that the line side is powered off, and then disconnects the energy storage system from the system power supply side. The entire energy storage system switches from the grid-connected operation mode to the off-grid operation mode at this time.

The system is in an off-grid operation mode after the ATS quick transfer switch is turned off, and the energy storage system supplies power to the emergency load at this time.

After the ATS fast switching switch detects that the power supply on the line side is restored, the switching switch is automatically switched on and has the synchronous closing function. At this time, the grid power supplies power to the emergency load and charges the energy storage battery pack.

In a second aspect, the present invention also provides a control method for a new emergency power supply system that replaces the offshore platform diesel generator system, including two operating processes in non-bypass mode and bypass mode, including the following steps:

(1) Non-bypass mode:

S01. The local controller first reads from the ATS whether the voltage and frequency of the power grid is normal. If it is normal, set the ATS fast switch to enter the grid-connected mode and start it, otherwise enter the off-grid mode and start it;

S02. After the ATS quick transfer switch enters the grid-connected mode and starts up, the local controller confirms whether the ATS quick transfer switch has completed grid-connected startup, and if the startup fails, the system shuts down;

S03. After the start-up of the ATS fast transfer switch is completed, the local controller reads whether the status of the energy storage bidirectional converter is normal. If it is normal, set the energy storage bidirectional converter to enter the grid-connected mode and start it. Otherwise, set the ATS fast transfer switch to be independent of the load. run;

Bypass mode:

S11. When the thyristor in the ATS fast transfer switch fails or the system is overhauled, the bypass circuit breaker can be closed to ensure the uninterrupted power supply of the load. At this time, the system works in the bypass mode;

S12. After the bypass mode is turned on, the local controller first detects whether the bypass switch in the ATS quick transfer switch is closed, and if not closed, the bypass mode is terminated;

S13. After detecting that the bypass switch is closed, the local controller reads from the ATS whether the grid voltage frequency is normal, and if it is not normal, end the bypass mode;

S14. After detecting that the grid voltage and frequency are normal, the local controller is set to bypass mode and starts, and executes the bypass operation strategy;

S15. After the start-up of the ATS fast transfer switch is completed, the local controller reads whether the state of the energy storage bidirectional converter is normal. If it is normal, set the energy storage bidirectional converter to enter the grid-connected mode and start it. Otherwise, set the ATS fast transfer switch to be independent of the load. run.

As a preferred technical solution of the present invention, step S01 also includes:

S001. After the local controller sets the ATS fast switching switch to enter the off-grid mode and starts it, the local controller confirms whether the ATS fast switching switch has completed off-grid startup, and if the startup fails, the system will shut down;

S002. After the start-up of the ATS fast switching switch is completed, the local controller reads whether the state of the energy storage bidirectional converter is normal, and if it is normal, set the energy storage bidirectional converter to enter the off-grid mode and start it, otherwise the local controller executes the system shutdown command;

S003. After the energy storage bidirectional converter completes the off-grid operation, the local controller detects whether the energy storage battery pack is in the discharge limit state. If so, the system shuts down, otherwise the energy storage battery pack starts to discharge the emergency load.

As a preferred technical solution of the present invention, in the non-bypass mode, if the energy storage bidirectional converter and the ATS fast transfer switch fail, the local controller executes the system shutdown command; in the non-bypass mode, when the local The controller monitors that the voltage and frequency of the power grid return to normal, the energy storage bidirectional converter switches to the grid-connected mode, the local controller switches to the grid-connected mode, and the ATS fast transfer switch completes the seamless switching from VF to PQ.

As a preferred technical solution of the present invention, in non-bypass mode or bypass mode, after the energy storage bidirectional converter completes grid-connected operation, the local controller detects whether the energy storage battery pack is fully charged, and sets The SOC enters the protection mode and stops charging, otherwise it continues to charge the energy storage battery pack; in non-bypass mode or bypass mode, if the ATS fast transfer switch fails, the local controller executes the system shutdown command or ends the bypass mode .

As a preferred technical solution of the present invention, in the non-bypass mode, when the local controller detects that the grid voltage frequency is abnormal, the energy storage bidirectional converter switches to the off-grid mode, and the local controller switches to the off-grid mode , ATS fast switching switch to complete the seamless switching from PQ to VF.

As a preferred technical solution of the present invention, in non-bypass mode or bypass mode, when the ATS fast transfer switch operates independently with load, the local controller judges in real time whether the ATS fast transfer switch is faulty, and if there is a fault, the local The controller executes the system shutdown command.

As a preferred technical solution of the present invention, in the bypass mode, and when the ATS fast transfer switch operates independently with load, and the local controller detects that the bypass switch is closed, the bypass mode ends.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention provides a new emergency power supply mode, which solves the problems of poor stability and difficult operation and maintenance of the diesel power generation system on the offshore platform, and can effectively reduce the cost of going out to sea for operation and maintenance after the diesel power generation system is in operation. The need for emergency power supply on offshore platforms. After the energy storage system is integrated into the emergency power supply system of the offshore wind farm, ① the degree of electrification is relatively high, and the switching response speed can reach the millisecond level as quickly as possible by switching the switch quickly. ②The energy storage system manages and monitors the main equipment and battery equipment in real time through the PCS energy storage bidirectional converter monitoring and energy storage management system. Realize "remote monitoring" and on-site "unmanned" operation and maintenance. After a loss of power consumption, the system will automatically switch to charge after the grid restores power supply, and does not need to manually go to sea to replenish diesel after the loss, like diesel generators. Therefore, the combination of energy storage system and offshore platform emergency power system is of great significance.

Description of drawings

Fig. 1 is a schematic diagram of the electrical principle of the system of the present invention.

Fig. 2 is a control flow chart of the non-bypass mode of the present invention.

Fig. 3 is a flow chart of bypass mode control in the present invention.

Reference signs: 1-isolated step-up transformer; 2-energy storage bidirectional converter; 3-energy storage battery pack; 4-energy storage load controller; 5-dual power switching device; 6-ATS fast switching switch; 7 -Low-voltage power distribution system; 8-emergency load bus; 9-emergency load incoming line; 10-emergency load feeder.

Implementation

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention will be described below in conjunction with specific examples, but it should be understood that the accompanying drawings are for illustrative purposes only, and cannot be interpreted as an explanation of this patent. limit.

The present invention will be further described below in conjunction with accompanying drawings 1-3 and the embodiments, but it is not used as a basis for limiting the present invention.

As shown in Figure 1, the present invention provides a new emergency power system that replaces the offshore platform diesel generator system, and the emergency power system includes energy storage system equipment, low-voltage power distribution system equipment and auxiliary system equipment; energy storage system equipment It is mainly composed of isolation step-up transformer 1, energy storage bidirectional converter 2, energy storage battery pack 3, local controller, energy storage load controller 4, dual power switching device 5 and ATS fast switching switch 6; low-voltage power distribution system 7 The equipment is mainly composed of a low-voltage power distribution system 7 and an emergency power distribution system; the output terminal of the low-voltage power distribution system 7 is connected to the dual power switching device 5, and the output terminal of the dual power switching device 5 is connected to the ATS fast switch 6; the ATS fast switch The first output terminal of 6 is connected to the emergency power distribution system, and the second output terminal of ATS fast transfer switch 6 is connected to the isolation step-up transformer 1 and charged to the energy storage battery pack 3 through the energy storage bidirectional converter 2, and The output terminal of the isolation step-up transformer 1 is connected to the emergency power distribution system, which can be used to control the switching between the grid-connected mode and the off-grid mode through the cooperation of the ATS quick switch switch 6 and the local controller.

The low-voltage power distribution system 7 is configured with two station transformers, and two sections of low-voltage power distribution buses are set. One station transformer is connected to the low-voltage section I busbar, and the other station transformer is connected to the low-voltage section II busbar. Segments are connected by couplings.

The emergency power distribution system includes an emergency load bus 8 , an emergency load incoming line 9 and an emergency load feeder 10 .

The auxiliary system equipment includes a fire control system and an environment control system, the fire control system includes fire monitoring equipment and fire extinguishing equipment, and the environment control system includes ventilation and temperature control equipment. The fire control system includes fire monitoring equipment and fire extinguishing equipment. Fire monitoring uses two types of automatic fire alarm detection equipment, photoelectric smoke and photoelectric temperature. Time to detect electrical fires and the ability to extinguish electrical fires. The fire detector tube is wound on the battery rack and inside the control panel cabinet. When the temperature in the energy storage battery pack 3 or the equipment panel cabinet rises to an abnormal temperature, the fire detector tube will act to complete fire protection for related equipment.

The environmental control system is equipped with ventilation and temperature control equipment. Considering the operation sensitivity of the energy storage battery to temperature and humidity, too high or too low temperature will cause the battery capacity to decline faster, the self-discharge rate will increase, and the capacity utilization rate will be greatly reduced. . The energy storage battery room of the present invention adopts a constant temperature and humidity design, and a ventilation and air conditioning system is installed to keep the indoor ambient temperature constant in an environment suitable for equipment operation, so as to ensure that the battery system works within a suitable temperature range.

As shown in Figure 2, in the non-bypass mode, the local controller first reads whether the grid voltage frequency is normal from the ATS, and if it is normal, set the ATS fast switch 6 to enter the grid-connected mode and start it, otherwise set the ATS fast switch 6 to enter Off-grid mode and start.

After the ATS fast switch 6 enters the grid-connected mode and starts up, the local controller confirms that the ATS fast switch 6 has completed the grid-connected startup, otherwise the ATS fast switch 6 sends a grid startup failure signal, and the system shuts down.

After the start of the ATS fast transfer switch 6 is completed, the local controller reads whether the state of the energy storage bidirectional converter 2 is normal. If it is normal, the local controller sets the energy storage bidirectional converter 2 to enter the grid-connected mode and starts it, otherwise it sets the ATS fast switching Switch 6 operates independently with load.

After the energy storage bidirectional converter 2 completes the grid-connected operation, the local controller detects whether the energy storage battery pack 3 is fully charged. If it is fully charged, the local controller sets the SOC to enter the protection mode and stops charging; otherwise, continue to charge the energy storage battery pack 3. Charge.

During the independent operation of the ATS fast transfer switch 6 with load, the local controller judges in real time whether the ATS fast transfer switch 6 is faulty. When the ATS fast transfer switch 6 fails during operation, the local controller executes the system shutdown command.

If the ATS fast transfer switch 6 fails, the local controller executes the system shutdown command; if the energy storage bidirectional converter 2 fails, the ATS fast transfer switch 6 is set to run independently with load.

When the local controller detects that the grid voltage frequency is abnormal, the energy storage bidirectional converter 2 switches to the off-grid mode, the local controller switches to the off-grid mode, and the ATS fast transfer switch 6 completes the seamless switching from PQ to VF.

After running in off-grid mode, the local controller detects whether the energy storage battery pack 3 is in the discharge limit state, and if so, the system shuts down; otherwise, the energy storage battery pack 3 starts to discharge the emergency load.

If the energy storage bidirectional converter 2 and the ATS fast transfer switch 6 fail, the local controller executes the system shutdown command.

When the local controller monitors that the grid voltage and frequency return to normal, the energy storage bidirectional converter 2 switches to the grid-connected mode, the local controller switches to the grid-connected mode, and the ATS fast transfer switch 6 completes the seamless switching from VF to PQ. After that, repeat the grid-connected control strategy process.

As shown in Figure 2, in the non-bypass mode, the local controller first reads whether the grid voltage frequency is normal from the ATS, and sets the ATS fast switch 6 to enter the grid-connected mode, otherwise sets the ATS fast switch 6 to enter the off-grid mode .

After the ATS fast switching switch 6 enters the off-grid mode and starts, the local controller confirms that the ATS fast switching switch 6 completes off-grid startup, otherwise the ATS fast switching switch 6 sends an off-grid startup failure signal, and the system shuts down.

After the start-up of the ATS quick transfer switch 6 is completed, the local controller reads whether the status of the energy storage bidirectional converter 2 is normal. If normal, the local controller sets the energy storage bidirectional converter 2 to enter the off-grid mode and start it, otherwise the local controller executes System shutdown command.

After the energy storage bidirectional converter 2 completes the off-grid operation, the local controller detects whether the energy storage battery pack 3 is in the discharge limit state, and if so, the system shuts down; otherwise, the energy storage battery pack 3 starts to discharge the emergency load.

If the energy storage bidirectional converter 2 and the ATS fast transfer switch 6 fail, the local controller executes the system shutdown command.

When the local controller monitors that the grid voltage and frequency return to normal, the energy storage bidirectional converter 2 switches to the grid-connected mode, the local controller switches to the grid-connected mode, and the ATS fast transfer switch 6 completes the seamless switching from VF to PQ.

After running in the grid-connected mode, the local controller detects whether the energy storage battery pack 3 is fully charged. If it is fully charged, the local controller sets the SOC to enter the protection mode and stops charging; otherwise, continue to charge the energy storage battery pack 3 .

If the ATS fast transfer switch 6 fails, the local controller executes the system shutdown command; if the energy storage bidirectional converter 2 fails, the ATS fast transfer switch 6 is set to run independently with load.

When the local controller detects that the grid voltage frequency is abnormal, the energy storage bidirectional converter 2 switches to the off-grid mode, the local controller switches to the off-grid mode, and the ATS fast transfer switch 6 completes the seamless switching from PQ to VF. After that, repeat the grid-connected control strategy process.

When the thyristor in the ATS fast transfer switch 6 fails or the system is overhauled, the bypass mode starts to operate.

As shown in FIG. 3 , after the bypass mode is turned on, the local controller first detects whether the bypass switch in the ATS fast transfer switch 6 is closed, and if not, the bypass mode ends.

After detecting that the bypass switch is closed, the local controller reads from the ATS whether the grid voltage frequency is normal, and if not, the bypass mode ends.

When it is detected that the grid voltage and frequency are normal, the local controller is set to bypass mode and starts to execute the bypass operation strategy.

After the start of the ATS fast transfer switch 6 is completed, the local controller reads whether the state of the energy storage bidirectional converter 2 is normal. If it is normal, the local controller sets the energy storage bidirectional converter 2 to enter the grid-connected mode and starts it, otherwise it sets the ATS fast switching Switch 6 operates independently with load.

After the energy storage bidirectional converter 2 completes the grid-connected operation, the local controller detects whether the energy storage battery pack 3 is fully charged. If it is fully charged, the local controller sets the SOC to enter the protection mode and stops charging; otherwise, continue to charge the energy storage battery pack 3. Charge.

During the independent operation of the ATS fast transfer switch 6 with load, the local controller judges in real time whether the ATS fast transfer switch 6 is faulty. When the ATS fast transfer switch 6 fails during operation, the local controller executes the system shutdown command.

If the energy storage bidirectional converter 2 fails, the ATS fast transfer switch 6 is set to run independently with load; if the ATS fast transfer switch 6 fails, the bypass mode ends.

When the local controller detects that the bypass switch is closed, the bypass mode ends.

According to the description and drawings of the present invention, those skilled in the art can easily manufacture or use a new emergency power supply system of the present invention that replaces the diesel generator system of the offshore platform, and can produce the positive effects recorded in the present invention.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any simple modifications and equivalent changes made to the above embodiments according to the technical essence of the present invention all fall within the scope of the present invention. within the scope of protection.

Claims (2)

1. An emergency power supply system for replacing an offshore platform diesel generator system, which is characterized in that: the system comprises energy storage system equipment, low-voltage power distribution system equipment and auxiliary system equipment; the energy storage system equipment mainly comprises an isolation step-up transformer, an energy storage bidirectional converter, an energy storage battery pack, a local controller, an energy storage load controller, a dual-power switching device and an ATS fast switching switch; the low-voltage power distribution system equipment mainly comprises a low-voltage power distribution system and an emergency power distribution system; the output end of the low-voltage distribution system is connected to a dual-power switching device, and the output end of the dual-power switching device is connected to an ATS quick change-over switch; the first path of output end of the ATS fast switching switch is connected to the emergency power distribution system, the second path of output end of the ATS fast switching switch is connected to the isolation step-up transformer and charges the energy storage battery pack through the energy storage bidirectional converter, and the output end of the isolation step-up transformer is connected to the emergency power distribution system, and the ATS fast switching switch and the local controller can be matched to control switching of a grid-connected mode and an off-grid mode;

the emergency power distribution system comprises an emergency load bus, an emergency load incoming line and an emergency load feeder line; the energy storage load controller is a PLC controller;

the control method of the novel emergency power supply system for replacing the offshore platform diesel generator system is characterized by comprising two operation processes in a non-bypass mode and a bypass mode, and the control method is characterized by comprising the following steps:

non-bypass mode:

s01, the local controller firstly reads whether the voltage frequency of the power grid is normal from the ATS, if so, the ATS fast change-over switch is set to enter a grid-connected mode and started, otherwise, the ATS fast change-over switch enters an off-grid mode and is started;

s02, after the ATS quick change-over switch enters a grid-connected mode and is started, the local controller confirms whether the ATS quick change-over switch completes grid-connected starting or not, and if the starting fails, the system is stopped;

s03, after the ATS fast change-over switch is started, the local controller reads whether the state of the energy storage bidirectional converter is normal, if so, the energy storage bidirectional converter is set to enter a grid-connected mode and is started, otherwise, the ATS fast change-over switch is set to operate independently with a load;

bypass mode:

s11, when a thyristor in the ATS fast change-over switch fails or the system overhauls, the bypass breaker can be closed to ensure uninterrupted power supply of the load, and the system works in a bypass mode at the moment;

s12, after the bypass mode is started, the local controller firstly detects whether a bypass switch in the ATS quick change-over switch is closed or not, and if not, the bypass mode is ended;

s13, after detecting that the bypass switch is closed, the local controller reads whether the voltage frequency of the power grid is normal or not from the ATS, and if not, the bypass mode is ended;

s14, after detecting that the voltage frequency of the power grid is normal, setting a local controller into a bypass mode, starting the local controller, and executing a bypass operation strategy;

s15, after the ATS fast change-over switch is started, the local controller reads whether the state of the energy storage bidirectional converter is normal, if so, the energy storage bidirectional converter is set to enter a grid-connected mode and is started, otherwise, the ATS fast change-over switch is set to operate independently with a load;

step S01 further includes:

s001, after the local controller sets the ATS quick change-over switch to enter the off-network mode and starts, the local controller confirms whether the ATS quick change-over switch finishes off-network starting or not, and if the starting fails, the system is stopped;

s002, after the ATS fast change-over switch is started, the local controller reads whether the state of the energy storage bidirectional converter is normal, if so, the energy storage bidirectional converter is set to enter an off-grid mode and started, otherwise, the local controller executes a system shutdown command;

s003, after the energy storage bidirectional converter finishes off-grid operation, detecting whether an energy storage battery pack is in a discharge limit state or not by a local controller, if so, stopping the system, otherwise, starting discharging the emergency load by the energy storage battery pack;

in a non-bypass mode, if the energy storage bidirectional converter and the ATS fast switch fail, the local controller executes a system shutdown command; in a non-bypass mode, when the local controller monitors that the voltage frequency of the power grid is recovered to be normal, the energy storage bidirectional converter is converted into a grid-connected mode, the local controller is converted into the grid-connected mode, and the ATS fast change-over switch finishes seamless switching from VF to PQ;

in a non-bypass mode or bypass mode, after the energy storage bidirectional converter completes grid-connected operation, the local controller detects whether the energy storage battery pack is fully charged, if so, the SOC is set to enter a protection mode, and charging is stopped, otherwise, the energy storage battery pack is continuously charged; in the non-bypass mode or the bypass mode, if the ATS quick change-over switch fails, the local controller executes a system shutdown command or ends the bypass mode;

in a non-bypass mode, when the local controller monitors that the voltage frequency of the power grid is abnormal, the energy storage bidirectional converter is converted into an off-grid mode, the local controller is converted into the off-grid mode, and the ATS fast switch finishes seamless switching from PQ to VF;

in a non-bypass mode or a bypass mode, when the ATS quick change-over switch operates independently with a load, the local controller judges whether the ATS quick change-over switch fails in real time, and if so, the local controller executes a system shutdown command;

in the bypass mode, and when the ATS fast switch operates independently with the load, the local controller detects that the bypass switch is closed, the bypass mode is ended.

2. An emergency power supply system for replacing an offshore platform diesel generator system according to claim 1, wherein: the auxiliary system equipment comprises a fire control system and an environment control system, wherein the fire control system comprises a fire monitoring device and a fire extinguishing device, and the environment control system comprises a ventilation and temperature control device.

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